Experimental Study of Electric Vehicle Yaw Rate Tracking Control Based on Differential Steering

This paper investigates the experimental study of differential steering control of a four-wheel independently driven (FWID) electric vehicle (EV) based on the steer-by-wire (SBW) system. As each wheel of FWID vehicle can be independently driven, differential steering is realized by applying different driven torques to the front-two wheels. Firstly, the principle of the differential steering is analyzed based on the SBW system. When the differential steering is activated, the driver’s steering request is sent to the vehicle’s ECU. Then, the ECU gives different control signals to the front-left and front-right wheels, generating an external steering force on the steering components. The external steering force pushes the steering components to turn corresponding to the driver’s request. Secondly, to test the feasibility of differential steering, a FWID EV is assembled and the vehicle is equipped with four independently driven in-wheel motors. The corresponding control system is designed. Finally, the field test of the vehicle based on the proposed differential steering control strategy is performed. In the experiment, the fixed yaw rate tracking and varied yaw rate tracking maneuvers are employed. In the fixed yaw rate tracking, the vehicle can track the desired yaw rate well with differential steering. In addition, the vehicle can track the varied yaw rate with proposed differential steering. The test results confirm the feasibility and effectiveness of the differential steering. By using the differential steering, a backup steering is established without additional components; thus, the costs can be reduced and the reliability of the vehicle steering system can be enhanced, significantly.

Mechatronic Design of a Four-Wheel drive mobile robot and differential steering

This paper presents, the development of an autonomous mobile robot with a four-wheel drive and differential locomotion. The mobile robot was developed in the Machines and Industrial Equipment Department from the Engineering Faculty of Sibiu. The main purpose of developing this type of mobile platform was the ability to transport different types of cargo either in industrial spaces or on rough terrain. Another important objective was that this platform could be driven in confined or tight spaces where a high degree of manoeuvrability is necessary. The great advantage of this type of mobile platform is the ability to navigate through narrow spaces due to the type of locomotion implemented. The fact that the robot has four driving wheels gives it the ability to travel on rough surfaces and easily bypass obstacles. Another great advantage of the developed mobile robot is that it has a reconfigurable structure. The drivetrain is interchangeable, it can adopt both classic wheels and Mecanum wheels. The first part of the paper presents some general aspects concerning mobile robots and two types of traction wheels used in mobile robotic structures. Subsequently, the paper presents the steps taken in the development of the mobile wheeled platform. At the end of the paper, the electronic part that will be implemented in the structure of the robot is described. The command and control of the entire mobile platform will be described in some future work.